EFFECTS OF DIETARY KRILL HYDROLYSATES ON GROWTH PERFORMANCE,BODY COMPOSITION AND RELATED ENZYME ACTIVITIES OF JUVENILE TURBOT (SCOPHTHALMUS MAXIMUS L.)

The current study investigated the effects of dietary krill hydrolysates on growth performance, body compo-sition and related enzyme activities of juvenile turbot (Scophthalmus maximus L.) with a 10-week feeding trial using indoor flowing-through seawater system. Three isonitrogenous and isolipidic diets were formulated to contain 0 (Control), 5% (LKH), 10% (HKH) krill hydrolysates for substitution of fish meal protein in basal diet that includes 30% fish meal, respectively. The results showed that the specific growth rate (SGR), feed efficiency rate (FE), protein efficiency ratio (PER) and protein productive value (PPV) in HKH group were significantly higher than those in the control group, but the feed intake (FI) was significantly lower than that of the control group. HKH supplementation had significantly higher whole-body moisture, whole-body crude protein contents and whole-body lipid contents than those in the control group (P<0.05). Both LKH and HKH groups significantly enhanced the muscle total amino acids contents and essential amino acids content compared with control group (P<0.05). Compared with the control group, both LKH and HKH significantly induced glutamic oxalacetic transaminase (GOT) activities in liver but not GOT activities in serum. HKH group showed the highest glutamic-pyruvic transaminase (GPT) activities in liver and the lowest GPT activities in serum. HKH group significantly increased amylase activity in intestines. The increasing amount of krill hydrolysates supplied in diet first decreased and then increased trypsin activities in pyloric caecum and intestines, and HKH group had significantly higher trypsin activities in pyloric caecum and intestines than those in the control group. In conclusion, 10% krill hydrolysates supplementation in diets could promote growth performance, amino acid metabolism as well as digestion and absorption of juvenile turbot.